CN117867929A

CN117867929A - Method for braking a compactor and compactor

Info

Publication number: CN117867929A
Application number: CN202311317786.5A
Authority: CN
Inventors: A·德尔蔡特
Original assignee: Bomag GmbH and Co OHG
Current assignee: Bomag GmbH and Co OHG
Priority date: 2022-10-12
Filing date: 2023-10-11
Publication date: 2024-04-12
Also published as: DE102022210736A1; US20240123952A1; EP4353906A1

Abstract

The invention relates to a method for braking a compactor (1) operated by an electric motor (4). The invention further relates to a compactor (1), in particular a twin-drum compactor, a single-drum compactor or a refuse compactor, for carrying out the method (40).

Description

Method for braking a compactor and compactor

Technical Field

The invention relates to a method for braking a compactor operated by an electric motor, the compactor having a hydraulic system, in particular a twin-drum compactor, a single-drum compactor or a trash compactor. The invention also relates to a compactor for carrying out the method.

Background

Compactors of this type are, for example, configured as rollers, in particular twin-roller rollers, rubber-wheel rollers or single-roller rollers. The compactor is used in road or street construction to compact foundations or ground surfaces, such as asphalt layers or lands. For this purpose, the compacting machine generally has a compacting roller, which is configured, for example, as a roller with a hollow cylindrical base body, and with which the compacting machine is moved over the ground. For example, such compaction rollers can also be vibrated by vibration exciters in order to thereby influence the compaction and to achieve dynamic compaction beyond purely static compaction. The compacting roller may also be used in combination with a wheel, such as a rubber wheel or other running gear. Furthermore, compactors are known which have only wheels, for example so-called rubber-wheel rollers, which are likewise used in road construction. Furthermore, so-called refuse compactors for compacting refuse landfills are known, which have roller-like wheel arrangements for compacting the ground. Compactors of this type are generally configured to be self-propelled and comprise a drive motor, which is generally an internal combustion engine, for example a diesel internal combustion engine. A drive scheme widely used for such compactors consists in that the drive motor drives a hydraulic system of the compactor or one or more hydraulic pumps which in turn supply hydraulic drive to hydraulic travel motors at the wheels or compacting drums via a suitable line system. The hydraulic pump responsible for the travel drive hydraulic circuit is also called a travel pump. In the field of compactors, electric machines are increasingly used as an alternative to internal combustion engines serving as main drives. In this case, the hydraulic system of the compactor is typically driven by an electric motor.

When an internal combustion engine, for example a diesel engine, is used, the internal combustion engine provides or builds up a bearing torque at any time during operation, so that this torque can be used reliably for braking the compactor. During braking or during a slope travel, the hydraulic travel motor of the compactor acts as a pump, so that the torque applied to the travel motor is transmitted to the travel pump, which then acts as a motor. In practical use, the bearing moment of the internal combustion engine is used in such a compactor to support/counteract such a torque exerted on the travel pump, as a result of which the compactor is braked overall. This effect is also commonly referred to as "engine braking". In switching from using an internal combustion engine to an electric-motor-operated compactor, it is difficult to reliably establish a supporting or braking torque by the electric motor that can be used to brake the compactor. In this way, for example, a reduced bearing moment can occur as a function of the charge of the battery or also as a function of a reduction in the power of the motor and/or the inverter. This in turn has an adverse effect on the braking performance of the compactor and may lead to risks and safety risks. In addition, due to the significantly reduced moment of inertia of the electric motor compared to the internal combustion engine, high overspeeds may occur on the electric motor, so that when the hydraulic transmission in the drive is unchanged, an increase in the driving speed occurs and thus the maximum permissible rotational speed of the hydraulic component is exceeded. Furthermore, in particular during heavy or frequently repeated braking, overheating of the motor, the inverter and/or the battery can occur, in particular, as a result of the input of electrical energy which is obtained by regeneration (regeneration). This may be done to the extent that the compactor must predictably cease operation or that damage to parts of the compactor may occur.

Disclosure of Invention

The object of the present invention is therefore to provide a possibility for achieving a reliable, efficient and safe braking in a compactor that is driven by an electric motor and has a hydraulic or electric travel drive.

The object is achieved with a method and a compactor according to the independent claims. Preferred developments are given in the dependent claims.

One aspect of the invention thus relates to a method for braking a compactor operated with an electric motor, in particular a twin-drum compactor, a single-drum compactor, a rubber-wheel compactor or a trash compactor. The method according to the invention can be carried out, for example, at least in part, by an in particular electronic control device of the compactor. The control device may be part of or be the on-board computer of the compactor. The compactor is operated by an electric motor, which is, for example, the main drive source of the compactor. The electric motor can thus provide drive energy for operating the compactor, in particular for driving operation. The motor may in particular form a unique main drive source for the compactor. The electrical energy required to power the motor may be provided by a suitable accumulator, such as a battery. However, devices that produce electrical energy, such as fuel cells or internal combustion engines and/or generators, may also be employed. The generator may also be driven, for example, by an internal combustion engine, but the internal combustion engine is not mechanically connected directly to the drive train of the compactor. If an internal combustion engine is present as the main drive engine, at least the direct or indirect conversion of the mechanical energy generated by the internal combustion engine into electrical energy is thus firstly achieved on the output side starting from the internal combustion engine, which in turn is used at least for driving the hydraulic travel drive. In addition to the electrical components, such as the electric motor, which are powered by an electrical energy source, such as a battery, all the mechanical or hydraulic drive components and/or the compacting components of the compacting machine are preferably driven by the electric motor or other electric drive device. In a preferred embodiment, the electric machine can thus replace the internal combustion engine which has been used up to now as the main drive source. In other words, the compactor according to the invention is therefore also preferably designed completely free of internal combustion engines, in particular as a travel drive motor, or on the output side of the electric machine as a "travel drive without internal combustion engine". The electric motor drive of the compactor, in particular of the travel drive, can be achieved indirectly with an electric motor, for example by driving a hydraulic pump by means of an electric motor, which in turn leads hydraulic fluid via a suitable hydraulic circuit to a hydraulic motor, which in turn forms the travel motor. However, it is also possible to provide that the compactor is driven directly by a motor, in that the running drive of the running device, such as, for example, a roller and/or a rubber wheel, is carried out by a running motor.

On the basis of this, a method according to the invention for braking a compactor, in particular a twin-drum compactor, a single-drum compactor, a rubber-wheel compactor or a refuse compactor, which is operated at least partially by means of an electric motor, is provided, which comprises the following steps: driving the running gear (directly or indirectly) with a motor; determining an actual value of an operating parameter; determining an expected value of the operating parameter; comparing the actual value of the operating parameter with the expected value of the operating parameter; if the actual value of the operating parameter differs from the desired value, in particular if the actual value is greater than the desired value of the operating parameter, a braking torque is generated by means of a hydraulic throttle valve in a brake hydraulic circuit, which comprises a brake hydraulic pump, which throttle valve is arranged in a hydraulic line with the hydraulic pump; and means for transmitting said braking torque from the braking hydraulic pump to the driving device directly or indirectly via a mechanical coupling. Details regarding the individual steps are also described in detail below. It is important that by means of the brake hydraulic circuit and the throttle valve, the flow cross section of which can be adjusted in an ideal manner by the control device, a bearing moment can be generated which can ultimately be transmitted via a mechanical connection to the device that directly or indirectly drives the driving device and thus ultimately to the driving device. The means for directly driving the driving device is, for example, an electric motor which drives the rotational movement of at least one of the driving devices via a purely mechanical drive train or directly via a shaft. The device for indirectly driving the driving device is, for example, an electric motor which drives at least one of the driving devices via at least two energy conversion steps, in particular from electric energy to hydraulic energy and subsequently from hydraulic energy to mechanical energy. The hydraulic throttle valve is preferably designed such that it is steplessly adjustable over its opening cross section within an adjustment range. For this purpose, it can be provided in particular that the hydraulic throttle valve is designed as a proportional valve.

The method according to the invention thus comprises: an actual value of an operating parameter is determined or obtained. The operating parameter may be, for example, the rotational speed of the electric machine. This refers to, for example, the rotational speed of the motor driving the travel pump. Additionally or alternatively, the operating parameter may be a travel speed of the compactor. The actual value may be recorded, for example, by one or more rotational speed sensors on the electric machine and/or at least one travel motor of the travel drive hydraulic circuit. It can be provided that the respective rotational speed sensor is present on one road roller drum or on one wheel or on all road roller drums and/or on all wheels. Alternatively, the determination of the driving speed can also be carried out by means of a particularly optical scanning of the ground, for example by means of a camera. In particular, for this purpose, the distance travelled can be determined by comparing images taken sequentially in time over a certain time interval and the movement or driving speed can be calculated therefrom. In addition or alternatively, the operating parameter may also be a temperature, for example a temperature of the motor and/or the inverter or the converter and/or the battery. In this case, a temperature sensor may be provided on the electric machine and/or on the inverter or converter and/or on the battery. Additionally or alternatively, the operating parameter may also be the charge of the battery, for which purpose a charge sensor may be provided. In addition or alternatively, the operating parameter may also be the current strength through the motor and/or the inverter or converter. For this purpose, an ammeter may be provided at an appropriate position. Finally, in addition or alternatively, the operating parameter may also be a torque on the electric machine, which may be determined, for example, by a torque sensor on the electric machine. Alternatively, the parameters may also be one or more parameters which are each directly or indirectly associated with one of the mentioned parameters, or a combination of at least two of the mentioned parameters and/or associated parameters. The corresponding actual value is transmitted to the control device. The or each sensor is connected to the control device by a signal transmission in order to transmit an actual value or an actual measured value. This can be done either wired or also wireless, as is the case with the connection for signal transmission mentioned below.

Furthermore, the method according to the invention comprises: the desired value of the or each said operating parameter is determined or set. These values, in particular the rotational speed of the motor or the travel speed of the compactor, can be read, for example, directly or indirectly from the adjustment position and/or the change in the adjustment position of the driver's lever or from other control inputs made by an operator, for example, on a control device. If necessary, for example, if a desired rotational speed or driving speed for the working operation of the compactor is predefined, a corresponding desired value can also be derived from the current operating state of the compactor, so that the control device can derive a corresponding desired value from the current operating state. The temperatures of the various components and the charge of the battery and the current strength through the motor or inverter and the desired values for the torque on the motor can in particular also be derived from considerations or regulations preset for operational safety and/or manufacturer. Thus, these values must be kept, for example, within a range that is considered safe for continued operation of the compactor. This range may vary depending on the structural characteristics of the components. The determination of the appropriate specific desired values for these parameters is thus dependent on a number of individual factors and will be within the skills of the respective person skilled in the art.

Based on the determined actual value and the confirmed expected value, a comparison of the actual value with the expected value is made. The control device determines in particular in this step an operating state in which the actual value differs from the desired value, in particular in which the actual value exceeds the desired value. This may occur, for example, when the compactor is undesirably accelerated by external factors, such as, for example, because the compactor is moving exactly along a downhill path. In addition or alternatively, the desired value may also decrease below the actual value by, for example, the operator operating the driver's lever and decreasing the set travel speed to be adjusted (the travel speed corresponds to the desired value). Furthermore, the operation of the brake by the operator may also indicate that a reduction in the desired rotational speed or the desired travel speed occurs relative to the actual rotational speed or the actual travel speed. The increased temperature of the motor, inverter or converter or battery means that these components are subjected to excessive loads, for example, during braking, so that it is necessary to obtain braking power from the other components. If the charge of the battery is too great, the battery cannot receive, for example, electrical energy originating from regeneration, which occurs, for example, during braking, so that in this case the operation of the electric machine as a generator is likewise unsuitable for braking. The same applies to the current strength through the motor or inverter and the torque on the motor. If the amperage and torque are too high, braking power must be drawn by other components. Thus, when the actual value is greater than the desired value and the actual value should be lowered accordingly, there are operating conditions that are of primary concern in accordance with the present invention. In this case, the compactor may be in inertial operation (Schubbetrieb). This means that, for example, the travel motor of the travel drive hydraulic circuit is held in rotation by its mechanical coupling to the compacting roller or wheel of the compactor or is driven by said compacting roller or wheel at this time and thus acts as a pump. In this case, the hydraulic fluid fed in the travel drive circuit present at this time can be led via the line system of the travel drive hydraulic circuit to the travel pump, which in this operating state acts as a motor. The travel drive hydraulic circuit and other components of the drive train of the compactor, which are connected to the travel pump, for example, including the steering feed pump, are entrained during the coasting operation. As mentioned above, the compactor according to the invention preferably has only an electric motor as the travel drive and no internal combustion engine. The bearing torque which is normally provided reliably by the internal combustion engine, by means of which the corresponding torque on the travel pump acting as a motor in coasting operation can be counteracted or supported (counteracted), is therefore not present according to the invention and cannot be provided reliably by the electric machine.

In a particularly preferred embodiment of the invention, the hydraulic system of the compactor comprises a travel drive hydraulic circuit having at least one travel pump that can be driven by the electric motor. The travel pump supplies hydraulic fluid to a travel motor of a travel drive hydraulic circuit, such that the travel motor drives a compaction drum or wheel of the compactor into rotation and thereby moves the compactor over the ground to be compacted. The travel pump is not explicitly driven mechanically by an internal combustion engine, which may be present for the purpose of operating the generator, but is driven in particular only by an electric motor. The method according to the invention then preferably comprises driving the travel pump in the travel drive hydraulic circuit of the compactor by means of the motor. The travel drive hydraulic circuit is preferably configured as a closed hydraulic circuit. The travel pump is preferably configured as a pump with a variable delivery volume, for example, in order to be able to vary the travel speed of the compactor and/or the available travel drive torque. For this purpose, the driving pump may be a variable pump with a variable rotational speed and/or configured with a variable supply (schluckvolume). Additionally or alternatively, the travel hydraulic motor driven by the travel pump may be configured as a variable motor with a variable supply.

In this preferred embodiment, the method according to the invention may comprise, in particular, driving a steering feed pump in a steering hydraulic circuit of the compactor, for example, also by means of the electric motor or another electric motor or an electric drive. For example, the pump itself may have an electric drive. Additionally or alternatively, the steering feed pump is driven by the same motor that also drives the travel pump. The two pumps may in this case be arranged in a serial arrangement. The steering supply pump supplies hydraulic energy to a steering hydraulic circuit. A steering device is arranged in the steering hydraulic circuit. The steering device may be in particular a single-stage or multi-stage rotary valve type full hydraulic steering (lenkorbirol). Unlike the travel pump, the steering feed pump is preferably designed as a metering pump, for example as a gear pump. In this way, it is ensured that the steering device is supplied with hydraulic fluid in a consistent manner, so that a reliable steering is possible in all operating situations. In addition to supplying the steering hydraulic circuit, it can also be provided according to the invention that the steering supply pump also feeds hydraulic fluid into the travel drive hydraulic circuit. In this way, hydraulic fluid losses in the travel drive hydraulic circuit can be compensated. The steering feed pump is therefore the only pump which serves both as a steering pump for the steering hydraulic circuit and as a feed pump for the travel drive hydraulic circuit in a dual function. The steering feed pump may be designed, for example, as a fixed displacement pump, but may also be designed as a variable displacement pump. The steering hydraulic circuit is now a brake hydraulic circuit. Finally, it is also possible to provide for this preferred development that the steering feed pump is coupled directly to the travel pump by a mechanical coupling, in particular via a shaft. For example, the travel pump and the steering feed pump can each be operatively connected to a common output shaft of the electric motor, which can be designed for this purpose, for example, as a direct drive (Durchtrieb), or a mechanical coupling can be provided that is separate from the electric motor. If a mechanical coupling between the two pumps is maintained, coupling via the transmission can also be achieved. Torque can be transferred between the travel pump and the steering feed pump by a mechanical coupling between the two pumps. In other words, the method according to the invention thus also comprises transmitting torque forces between the travel pump and the steering feed pump via a mechanical coupling, in particular a direct mechanical coupling, between the two pumps. In this particular case, the steering feed pump is a brake hydraulic pump.

In the specific case described above (Fallkonstellatio), in particular when the actual value of the operating parameter is greater than the desired value, it is provided according to the invention that a braking torque is generated at the brake hydraulic pump, for example at the steering feed pump. This is achieved firstly by a hydraulic throttle valve arranged in the brake hydraulic circuit, which is arranged in the hydraulic line between the brake hydraulic pump, in particular the steering feed pump, and a tank outlet arranged downstream of the brake hydraulic pump. It may be provided that further components, such as, for example, steering devices, for example, a rotary valve type full hydraulic steering, which may be provided in the steering hydraulic circuit, are provided in the brake hydraulic circuit and/or are supplied by the brake hydraulic circuit. The steering hydraulic circuit thus also forms a brake hydraulic circuit at least partially at the same time in this case.

The throttle valve may be configured, for example, as a proportional pressure limiting valve, which is controlled in particular by the control device. By actuating the throttle valve, the control device can build up almost any pressure drop over the hydraulic throttle valve within system-related limits. In this way, a back pressure can be generated or regulated downstream of the brake hydraulic pump, in particular of the steering feed pump, or a flow resistance downstream of the brake hydraulic pump can be regulated, against which the pumping takes place. In other words, a braking torque is generated at this location. Due to the defined working volume of the brake hydraulic pump, in particular of the steering feed pump, or of the defined delivery volume of the brake hydraulic pump, in particular of the steering feed pump, at constant rotational speeds, the back pressure can be used in the brake hydraulic circuit, in particular in the steering hydraulic circuit, in the present arrangement for example for generating a bearing torque on the travel pump, and thus for the brake torque for the compactor. By means of the mechanical coupling of the brake hydraulic pump, in particular the steering feed pump, to the travel pump, a braking torque generated at the brake hydraulic pump, in particular the steering feed pump, during the coasting of the compactor is in particular transmitted directly, for example, to the travel pump of the travel drive hydraulic circuit and thus provides a supporting effect for the travel pump. Accordingly, the method according to the invention makes it possible in particular to transmit the braking torque directly from the steering feed pump via a mechanical connection to the travel pump of the travel drive hydraulic circuit or, in general, from the braking hydraulic pump to a device, in particular an electric motor, which directly or indirectly drives at least one of the travel devices. The magnitude of the braking torque provided can be adjusted almost arbitrarily and steplessly, for example, by changing the flow cross section or the pressure drop over the throttle valve by the control device. In particular, for this purpose, such a change in the flow cross section can be controlled, for example, by a corresponding energization of a throttle valve or a proportional pressure limiting valve. The braking torque value set by the control device is preferably proportional to the difference between the actual value and the desired value of the operating parameter. Such regulation can be achieved, for example, by different regulation structures known per se in the prior art, for example by PI regulators, PID regulators, state-based regulators, etc.

However, when the actual value of the operating parameter is greater than the desired value, the hydraulic throttle valve does not always have to be activated immediately. In this way, for example, an acceptable range can be predefined, within which the actual value of the operating parameter can be higher than the desired value without immediately establishing a braking torque on the braking hydraulic pump, in particular the steering feed pump. The control device actuates the hydraulic throttle valve only if the actual value of the operating parameter, for example, leaves the tolerance range upwards, in order to generate a braking torque on the braking hydraulic pump, in particular the steering feed pump. The tolerance range may be sized to be fixed or dynamically adapted to the operating conditions. For example, the control device can calculate a threshold value, which defines the tolerance range, which is higher than the desired value of the operating parameter, for example by a defined percentage value, in particular 5% or 10% or 15% or 20% or 25% or 30%. The throttle valve is actuated only when this threshold value is exceeded in order to generate a braking torque. In addition or alternatively, an allowable time, that is to say a predefined time period, may be provided, during which the actual value of the operating parameter may be greater than the desired value, without the control device actuating the throttle valve to generate a braking torque. The same applies to the case of leaving the allowable range, as described above. That is, the allowable range and the allowable time may be used together. That is, the throttle valve does not have to be operated immediately when the actual value of the operating parameter is higher than the desired value of the operating parameter. Instead, the end of the allowable time is first waited for. The control device actuates the throttle valve only if the corresponding threshold value is still exceeded after the end of the permissible time period, in order to generate a braking torque on the braking hydraulic pump, in particular the steering feed pump. The tolerance time may be, for example, at most 1s or at most 3s or at most 5s or at most 10s. Furthermore, the permissible time may be adapted dynamically as a function of the operating conditions of the compactor, for example as a function of the actual values of the operating parameters. In this way, for example, the allowable time may decrease as the travel speed increases, so as to ensure that a quick response of the entire system is achieved at high travel speeds.

According to a preferred embodiment, it can be provided that the braking torque provided at the brake hydraulic pump, in particular at the steering feed pump, is increased in proportion to the difference, as long as the difference between the actual value of the operating parameter and the desired value of the operating parameter increases. Furthermore, when the difference is reduced again, there is no need to immediately reduce the braking torque again. In contrast, it is preferably provided that the braking torque is kept constant after the braking torque has been increased, in particular in proportion to the difference, in particular even if the difference is reduced again. The braking torque is preferably kept constant until the actual value has fallen back to the desired value or below, that is to say until the difference has become zero. In this way, the reaction also takes place to a corresponding extent in the event of severe undesired accelerations or other deviations from the optimal operation of the compactor.

The method according to the invention brings about a series of advantages. For example, a braking torque can be supplied to the driving hydraulic circuit without a hydraulic throttle being provided for this purpose in the closed driving hydraulic circuit, but in the open steering hydraulic circuit. The heat present at the throttle valve is thus distributed in the hydraulic medium over a larger volume and also over a volume in the hydraulic tank, and can furthermore also be conducted out comparatively simply by means of a cooler, which is likewise arranged, for example, in the steering hydraulic circuit, in an ideal case downstream of the throttle valve and/or the rotary-valve full-hydraulic steering. As a result, the temperature of the motor, the inverter or the converter and the battery can also be reduced or at least the temperature rise thereof can be reduced. By taking the charge of the battery into account, the occurrence of overcharge can be avoided. By using a hydraulic throttle valve which can be actuated at will by the control device, a braking torque having almost any desired magnitude can be provided within the limits of the system, whereby the braking effect or braking action can also be set and can be varied over a wide range of actions. The invention thus allows a slower deceleration until a rapid emergency braking is reached before stopping the compactor. Furthermore, alternative braking possibilities, such as the use of dynamic service braking, require significantly more space and costs. Since the throttle valve can always be controlled such that sufficient hydraulic medium circulates in the steering hydraulic circuit, an uninterrupted, adequate supply of the steering system is ensured. Thus, there is no need to use one or more pilot valves, in particular in the steering hydraulic circuit. Furthermore, the system is particularly simple to construct and thus economical by using a steering feed pump which is usually already present in compactors.

The magnitude of the braking torque provided depends not only on the setting of the throttle valve, in particular its flow cross section, but also on the hydraulic pressure prevailing at the brake hydraulic pump, in particular the steering feed pump, and on the delivery volume of the brake hydraulic pump, in particular the steering feed pump. It may therefore be expedient to use a brake hydraulic pump, in particular a steering feed pump, with a variable delivery volume, in the present case a constant displacement pump being preferably used as the brake hydraulic pump, in particular the steering feed pump. A further possibility of increasing the braking torque provided can thus also be achieved in that the supply of the travel pump is reduced when the braking torque is transmitted. The travel pump is preferably configured as a pump with a variable supply and is likewise actuated, for example, by the control device, so that its supply can likewise be regulated by the control device. In coasting, the travel motor operates as a pump and thus delivers a defined volume of hydraulic fluid to the travel pump. The hydraulic fluid is then conveyed through the travel pump and drives the travel pump. If the supply quantity of the travel pump is reduced at this time, the rotational speed of the travel pump is increased in order to achieve a volume flow from the travel motor that is fed. This increased rotational speed is in turn transmitted to the steering feed pump by a direct mechanical coupling of the driving pump and the steering feed pump, as a result of which the transport volume per unit time of the steering feed pump is increased, as a result of which an increased braking torque is achieved. As a result, the braking torque can be increased during the braking process in general during coasting operation, in that the supply of the travel pump is reduced.

The driving hydraulic circuit and the steering hydraulic circuit are separate hydraulic circuits, between which hydraulic fluid is exchanged, if any, only via a common hydraulic fluid tank and, if necessary, a combined return line to the fluid tank. If necessary, however, a further connection between the travel drive hydraulic circuit and the steering hydraulic circuit may be present only in the supply line which starts from the steering hydraulic circuit and feeds hydraulic fluid into the travel drive hydraulic circuit in order to compensate, in particular, for leakage losses in the travel drive hydraulic circuit. In contrast, the two circuits preferably do not have a common functional unit which is driven by them in each case and are therefore operated in each case by a separate pump which is dedicated to the respective hydraulic circuit. In the case of compactors having additional hydraulic working devices, such as vibration or vibration exciters in the compacting drum, generally unbalanced mass exciters, it is preferably provided that a separate hydraulic working circuit is provided for the operation of the working devices. In other words, it may be preferable for the hydraulic system of the compactor to comprise a working hydraulic circuit, in particular an imbalance-driven hydraulic circuit, separate from the travel-driven hydraulic circuit and the steering hydraulic circuit, which is preferably operated only by a working pump separate from the steering feed pump. The working hydraulic circuit is therefore preferably also connected to the other hydraulic circuits of the compactor only via the hydraulic tank and optionally combined return lines leading to the tank. If other closed hydraulic circuits are present, these can also be supplied by the steering hydraulic circuit in order to compensate only for leakage losses. It is important that the working hydraulic circuit is in particular completely decoupled from the steering hydraulic circuit, so that it is also ensured that the steering system or the steering device is always supplied with hydraulic fluid continuously without the use of a pilot valve. The working pump operates only the working device provided in the working hydraulic circuit and does not operate other functional units, in particular in other hydraulic circuits. All the pumps mentioned, namely the travel pump, the steering feed pump and the working pump, can be driven by an electric motor. For example, the pumps are arranged on a common shaft of the electric motor or are connected to each other by a direct drive. At least the travel pump is always driven by the motor described here, which is likewise used for controlling the method. The steering feed pump and the working pump may optionally be driven by separate electric drives, for example separate motors, it being preferred here that at least the steering feed pump and the driving pump are driven by a common motor.

By providing a braking torque on the steering charge pump, the steering hydraulic circuit absorbs the kinetic energy of the compactor. As a result, the hydraulic fluid or hydraulic oil and other components of the steering hydraulic circuit are heated. In a preferred embodiment of the invention, it is now provided that an excessively high temperature rise of the steering hydraulic circuit, which may therefore be damaged, is not ensured by the provision of a braking torque on the steering feed pump. For this purpose, a threshold value can be defined for example for the temperature of the steering hydraulic circuit, in particular for the temperature of the hydraulic fluid. The threshold value is, for example, a maximum value, i.e. a temperature which should not be exceeded. In this case, it is preferable to set a temperature in the steering hydraulic circuit, for example, a temperature of the hydraulic fluid in the steering hydraulic circuit, and to generate no braking torque on the steering supply pump via the hydraulic throttle when the temperature in the steering hydraulic circuit is higher than a predetermined threshold value. In other words, it is checked whether the steering hydraulic circuit is able to absorb kinetic energy in the form of thermal energy. Only if this is the case, that is to say if the temperature in the steering hydraulic circuit is below the threshold value, is a braking torque provided according to the invention on the steering feed pump. This ensures that the steering hydraulic circuit and in particular the safety-relevant steering system does not overheat.

It may be advantageous if the return line or return line of the steering hydraulic circuit and the return line or return line of the travel drive hydraulic circuit for leakage merge and are jointly introduced into the tank. The components and installation space can thereby be saved, so that the system as a whole is simplified.

Preferably, it is provided that a rotational speed change (drehzahlu bersetzung) is performed when a braking torque is transmitted by a mechanical coupling from the braking hydraulic pump to a device that directly or indirectly drives the driving device, in particular to the driving pump or the driving motor. In this way, adaptation to the current rotational speed requirement can be achieved.

In a development of the at least one driving device driven by a driving hydraulic motor, it can furthermore be provided that the driving hydraulic motor can be coupled by a mechanical coupling to a brake hydraulic pump, in particular configured with an adjustable delivery volume, which is part of a brake hydraulic circuit separate from the driving hydraulic circuit, and that the hydraulic throttle is arranged in the brake hydraulic circuit, in particular downstream of the brake hydraulic pump, and that the generation of a braking torque on the brake hydraulic pump is achieved by the hydraulic throttle, and that the transmission of the braking torque from the brake hydraulic pump to the driving hydraulic motor of the driving hydraulic circuit is achieved via the mechanical coupling. This arrangement can be greatly simplified in that the only function of the brake hydraulic circuit and the brake hydraulic pump is to generate an additional braking or supporting moment as a function of the situation, as described above.

In principle, according to the invention, it may also be provided that the hydraulic accumulator is charged during the operating phase in which a braking torque is generated in the brake hydraulic circuit by the brake hydraulic pump. The stored hydraulic energy may be used later for functions of the compactor, such as, for example, enhancement functions, drive functions for additional equipment, etc.

The above object is also achieved by a compactor, in particular a twin-drum compactor, a single-drum compactor or a refuse compactor, having a hydraulic system, an electric motor and a control device which is configured for carrying out the method according to the invention. The control device can, for example, control all components of the compactor that participate in the method. At least by the control device, it is possible to determine an actual value of an operating parameter, to determine an expected value of the operating parameter, and to compare the actual value of the operating parameter with the expected value. Furthermore, the control device in particular actuates the throttle valve in order to generate a braking torque here. All the features, effects and advantages described herein of the method according to the invention are applicable in a transitive manner to the compactor according to the invention and vice versa. To avoid repetition, reference is made here only to the corresponding further description.

The compactor may have a travel drive hydraulic circuit with a motor-driven travel pump, which is in particular designed as a variable pump, that is to say with a variable or adjustable delivery volume. The travel pump is mechanically driven, for example, by an output shaft of an electric motor. The mechanical drive connection between the electric motor and the driving pump, for example in the form of an output shaft, is ideally clutch-free. The control of the variable displacement pump and in particular of the variable delivery volume is effected, for example, by the control device. The travel drive hydraulic circuit is preferably configured as a closed hydraulic circuit. The travel drive hydraulic circuit has at least one travel motor, in particular on the compaction drum and/or the wheels of the compactor, which runs from the volumetric flow of the travel pump to the torque for compacting the drum and/or the wheels. When the compactor is braked or driven down a slope, that is to say during the coasting of the compactor, the travel motor is rotated by a mechanical connection to the compacting roller and/or to the wheels and thus acts as a pump. This torque is transmitted by the closed hydraulic circuit to the travel pump, which acts as a motor. As already explained, the core of the invention is that this torque on the travel pump is supported/counteracted by a braking torque generated on the steering feed pump.

For this purpose, the compactor preferably has a steering feed pump in the steering hydraulic circuit, which is in particular also driven by the motor, which is in particular designed as a constant delivery volume, for example as a gear pump. The steering feed pump ensures that a certain volume flow is achieved in the steering hydraulic circuit, via which volume flow the steering device, such as, for example, a rotary valve type full hydraulic steering, is fed in particular. Furthermore, the steering feed pump is preferably designed for feeding hydraulic fluid into a travel drive hydraulic circuit, which is designed in particular as a closed circuit. This compensates for hydraulic losses in the drive hydraulic circuit and enables a cross-flow flushing. But no drive energy is introduced into the travel drive hydraulic circuit by the steering feed pump. The drive of the travel drive hydraulic circuit is only from the travel pump or, in coasting operation, from the compacting drum or wheels of the compactor. Therefore, the steering hydraulic circuit and the travel drive hydraulic circuit are configured separately from each other and are separated from each other.

The travel pump is preferably coupled to the steering feed pump by a mechanical coupling. In this way, torque can be transferred between the two pumps. In particular, the excess torque on the travel pump can be offset during the coasting operation by the braking torque on the steering feed pump. In order to generate the braking torque, a hydraulic throttle is preferably provided in the hydraulic line between the steering feed pump and the steering device of the steering hydraulic circuit. The hydraulic throttle valve is in particular designed to be controllable by the control device, in particular in such a way that by means of the control device it is possible to set what the flow barrier formed by the throttle valve should be. In other words, the pressure drop across the throttle valve can be regulated by the control device. The control device controls the throttle valve, for example, in such a way that the throttle valve does not form a flow barrier and no pressure drop exists across the throttle valve. In this case, no braking torque is generated either. However, the control device can also actuate the throttle valve, for example, in such a way that a pressure drop occurs across the throttle valve, as a result of which a braking torque is generated at the steering feed pump. The magnitude of this braking torque can be adjusted by the control device as required. In a preferred embodiment, the hydraulic throttle valve is configured as a proportional pressure limiting valve. This makes it possible on the one hand to reliably and desirably regulate the braking torque by the control device and on the other hand at the same time to ensure a continuous supply of sufficient volume flow to the steering device in the steering hydraulic circuit by corresponding actuation of the throttle valve. Depending on the current operating conditions, a desired braking torque may be provided in order to brake the compactor.

It can be provided that the hydraulic system of the compactor has, in addition to the travel drive hydraulic circuit and the steering hydraulic circuit, a hydraulic circuit with additional working devices for operating, which is separate from the travel drive hydraulic circuit and the steering hydraulic circuit. This may be, for example, a hydraulic circuit for operating a vibration exciter in the compacting cylinder. In this way, for example, it is preferable to provide a working hydraulic circuit having a working pump, which can be connected to the motor drive, separately from the travel drive hydraulic circuit and the steering hydraulic circuit. The working pump is therefore preferably driven by the motor and is mounted, for example, on the output shaft of the motor or on the direct drive of one of the further pumps. Alternatively, the working pump may be driven by an electric drive separate from the motor, for example another motor. By providing an additional working hydraulic circuit separate from the other hydraulic circuits in the hydraulic system of the compactor, the use of complex hydraulic circuits and components may be avoided. For this purpose, it is particularly important that no further working devices are provided in the steering hydraulic circuit, or are not operated by the steering feed pump, in addition to the throttle valve and the steering system. In this way, for example, pilot valves can be omitted in the steering hydraulic circuit. It is therefore also preferably provided that the steering feed pump and the hydraulic line supplied by the steering feed pump are configured without pilot valves.

In order for the control device to be able to control all components of the system and in particular also to be able to adapt the value of the braking torque provided at the steering feed pump to the current operating conditions of the compactor as required, different relevant adjustment amounts are provided to the control device. The following description relates to a motor that drives a travel pump. For this purpose, it is preferably provided that a rotational speed sensor is provided on the electric motor and/or on the drive motor of the drive hydraulic circuit, said rotational speed sensor being connected to the control device and transmitting its measured value to the control device. The rotational speed sensor is in particular designed to determine the actual rotational speed of the motor and/or the actual travel speed of the compactor or a parameter associated therewith. In addition or alternatively, a temperature sensor may be provided, for example, on the motor, on the inverter or converter or on the battery. A plurality of temperature sensors may be provided on a plurality of the members at the same time. In addition, a charge sensor may additionally or alternatively be provided on the battery and/or an ammeter may be provided for determining the actual current level through the motor and/or through the inverter or converter and/or a torque sensor may be provided on the motor. All of these sensors are connected to the control device and send their measured values to the control device. These measured values are used as input variables in the method according to the invention, in particular as actual values of the operating parameters. Furthermore, the control device is preferably configured to determine a desired value of the operating parameter, for example a desired rotational speed of the electric machine and/or a desired travel speed of the compactor and/or a desired temperature of the electric machine and/or the inverter or the converter and/or the battery and/or a desired charge of the battery and/or a desired current strength through the electric machine and/or the inverter or the converter and/or a desired torque on the electric machine or a parameter associated with the above-mentioned parameters. For this purpose, for example, the setting of the operating elements of the compactor, for example the position of the driver's lever, which can be adjusted by the operator and which specifies the desired travel speed, can be considered. Other desired values are derived for safety reasons. The desired value, for example the desired rotational speed or the desired driving speed, is used as a desired quantity in the method according to the invention, and the value of the input quantity is compared with the desired quantity. The control device determines, by means of a corresponding comparison, whether the compactor is currently in coasting, that is to say whether the compactor is currently braked or braked and/or is driven down a slope.

The control device is in particular designed to generate a braking torque on the steering feed pump via the hydraulic throttle when an actual value of the operating parameter, for example an actual rotational speed and/or an actual driving speed, or a parameter associated with the actual rotational speed or the actual driving speed, is greater than the desired value, for example a desired rotational speed and/or a desired driving speed, or a parameter associated with the desired rotational speed or the desired driving speed. The control device is configured to generate a braking torque on the steering feed pump via the hydraulic throttle when the compactor is in coasting mode and the control device confirms this by comparing the actual value with the desired value. In this way, the steering feed pump counteracts the torques occurring on the driving pump due to inertia via the mechanical coupling of the two pumps and thus replaces the conventional internal combustion engine according to the invention. In this way, a corresponding support torque or braking torque can also be provided in an electrically operated compactor. Thus, the hydrostatic drive with a static parking brake conventionally used can be retained without having to change to an expensive alternative.

A particularly space-saving and simple construction is achieved in that the return line of the steering hydraulic circuit and the return line of the travel drive hydraulic circuit and, if appropriate, also the return line of the working hydraulic circuit are configured to open jointly into the hydraulic tank. The corresponding return lines are thus integrated, so that only a single return line needs to be led to the hydraulic tank, whereby the installation space is saved and the system overall is of a simpler construction.

In addition or alternatively, it can be provided that a hydraulic accumulator is provided, which is connected to the brake hydraulic circuit, in particular to the steering hydraulic circuit, via an accumulator charging valve. This makes it possible to use the brake hydraulic circuit for charging the hydraulic accumulator, in particular during the phase when a braking torque is to be generated.

The compactor according to the invention additionally or alternatively comprises a traveling device which is driven directly by a hydraulic motor, in particular via a shaft, and a brake hydraulic pump of a brake hydraulic circuit which is mechanically connected to the hydraulic motor, in particular via a transmission chain. In addition or alternatively, the compactor may comprise a travel device directly driven by an electric motor, in particular via a shaft, and a coupling transmission via which the electric motor can be mechanically coupled to a brake hydraulic pump of a brake hydraulic circuit, in particular downstream of the brake hydraulic pump, comprising the hydraulic throttle. One such previously described arrangement may be assigned to each drum of the compactor.

In a further preferred development of the invention, the compactor may be configured such that each of the driving devices, in particular each of the compacting drums, comprises a separate brake hydraulic circuit and furthermore has at least one of the following features: each hydraulic circuit is provided with a separate hydraulic accumulator; a common hydraulic accumulator is present, which is connected to the at least two brake hydraulic circuits via a supply line via one or via a common accumulator charge valve; the throttle valves of the two brake hydraulic circuits can be actuated independently of one another, and the control device is configured such that it controls the two throttle valves independently of one another and/or taking into account the actual driving direction. This embodiment makes it possible in particular to control the braking torques acting on the front and rear drive devices, respectively, independently of one another, which are generated by the device described above. This may be advantageous in particular if the machine-specific moment of inertia present in the respective travel device varies as a function of the current travel direction of the compactor.

Drawings

The invention will be described in detail below with reference to embodiments shown in the drawings. Wherein schematically:

FIG. 1 shows a side view of a compactor, here a dual drum compactor;

FIG. 2 shows a side view of a compactor, here a single drum compactor;

FIG. 3 shows a side view of a compactor, here a trash compactor;

FIG. 4 shows a plot of a portion of a hydraulic system of a compactor machine that is relevant to a current situation;

FIG. 5 shows a schematic view of the control device and its connections to other components;

FIG. 6 illustrates the time course of different parameters in one exemplary application;

FIG. 7 shows a flow chart of the method;

FIG. 8 illustrates an alternative embodiment of a hydraulic system of a compactor;

FIG. 9 shows a simplified diagram of an alternative drive scheme;

FIG. 10 shows a simplified diagram of another alternative drive scheme; and

fig. 11 shows the time course of different parameters in another exemplary application.

Detailed Description

Identical or functionally identical components are denoted by the same reference numerals in the figures. The duplicate components need not be individually labeled in each figure.

Fig. 1, 2 and 3 show an exemplary representation of different compactors 1 according to the invention. Thus, in fig. 1, for example, a double-drum roller is shown, in particular a rotary-disc articulated double-drum roller, which is generally used for compacting asphalt. Alternatively, a hinged (knuckgelenkt) double drum roller or rubber wheel roller may also be used, the corresponding frame structure of which is known in the art. Fig. 2 shows a single drum roller having a front truck and a rear truck, which is typically used for compacting land. Fig. 3 also shows a trash compactor, such as is used on a landfill. The compactor 1 generally comprises a frame 3 with a drive table 2 and a running gear with which the compactor is moved in a working direction a or counter to the working direction over a ground 8 to be compacted. For this purpose, the double-drum roller according to fig. 1 has a front and a rear compacting drum 5 as a driving device 52, for example. The single-drum roller according to fig. 2 has, as a driving device 52, a compacting drum 5 at the front and rear wheels 7. The compaction drum 5 may optionally include vibration or shock actuators that affect compaction by the compaction drum 5. The refuse compactor according to fig. 3 has only wheels 7 similar to a drum and additionally comprises a push shovel 9 with which landfill material can be dispensed. All embodiments shown of the compactor 1 are driven by an electric motor 4 as the main drive or as the travel drive and additionally have a hydraulic system 6. Furthermore, all of the illustrated road rollers have a storage or fuel cell for electrical energy, which is referred to below as battery 32 by way of example. In order to carry out the method and also to control all relevant components of the compactor 1, the latter in particular also comprises a control device 10, which is part of or itself forms an on-board computer, for example. Furthermore, the control device 10 preferably comprises an operating element, such as a steering column or the like, by means of which an operator controls the compactor 1.

Fig. 4 shows an exemplary illustration of a part of a hydraulic system 6 of a compactor 1. All hydraulic pumps of the hydraulic system 6 are in the present embodiment preferably driven by the electric motor 4, in particular via an output shaft 28. The motor 4 is driven by a memory for electrical energy, for example a battery 32. An inverter 31 or converter may be provided between the motor 4 and the battery 32. For example, the electric motor 4 drives the travel pump 12 in this way, which is part of a travel drive hydraulic circuit 16, which is preferably configured to be closed. The travel drive hydraulic circuit 16 preferably comprises at least one travel motor 26 which converts the volumetric flow of the travel pump 12 into a drive torque for the travel device 55, in particular the compacting roller 5 or the wheels 7, for advancing the compactor 1 and transmits the drive torque to the travel device, for example via a shaft. In this case, the motor 4 is thus a device that indirectly drives the running device 55. The brake hydraulic pump 54, in particular the steering feed pump 13, is preferably likewise driven by the output shaft 28 of the electric motor 4. The steering feed pump 13 is preferably part of a brake hydraulic circuit 53, in the present case a steering hydraulic circuit 19, which in particular comprises a steering device 27, for example a rotary valve type full hydraulic steering. The steering feed pump 13 may be a fixed displacement pump. However, variable displacement pumps can also be used, so that the braking torque produced can also be varied by changing the delivery volume of the steering feed pump. A throttle valve 18 is preferably provided in the hydraulic line 25 between the steering feed pump 13 and the steering device 27. As is evident from the exemplary embodiment shown, the throttle valve can be designed as a proportional pressure limiting valve. Furthermore, a cooler 20, which cooperates with a fan, for example, and via which heat is conducted away from the hydraulic medium into the ambient air, may also be provided in the steering hydraulic circuit 19. It is important that there is a mechanical coupling 11 between the travel pump 12 and the steer feed pump 13. In the embodiment shown, this mechanical coupling 11 is realized, for example, by a direct transmission or by the two pumps being arranged together on the output shaft 28 of the electric motor 4. It is only important that torque can be transmitted from the travel pump 12 to the steering feed pump 13 and vice versa. Finally, the hydraulic system 6 preferably has a further hydraulic circuit, in particular a working hydraulic circuit 17 with a working pump 14, which is likewise driven by the electric motor 4 and in particular also via an output shaft 28 of the electric motor. The pumps 12 and 14 may be arranged in a series arrangement. The working hydraulic circuit 17 is configured, for example, as a vibration exciter for operating the compacting roller 5.

In principle, it is preferred according to the invention for the hydraulic fluid fed by the steering feed pump 13 to pass completely through the throttle 18 at least with the part of the fed hydraulic fluid fed by the steering feed pump 13 to the steering device 27 before it is fed to the steering device 27. The throttle valve is thus ideally arranged upstream of the steering device 27. The steering device 27 is thereby supplied with the same hydraulic fluid that has previously passed through the throttle 18. It may be provided that a portion of the hydraulic fluid fed by the steering feed pump 13 is tapped upstream of the throttle valve 18 for cross-flow flushing of the or each drive motor. The energization of throttle valve 18 and thus also the position of the throttle valve or its throttle effect can be controlled or regulated as a function of the rotational speed of the motor and/or the compactor speed.

As shown in fig. 4, it is preferable that the travel drive hydraulic circuit 16, the steering hydraulic circuit 19, and the working hydraulic circuit 17 each have their own pump dedicated to the circuit. In the respective circuit, hydraulic energy is therefore preferably generated only by the pumps associated with the respective circuit. However, steering feed pump 13 is preferably configured at the same time as a feed pump for driving hydraulic circuit 16. This means that the steering hydraulic circuit 19 preferably branches off from a supply line 23, which supplies the travel drive hydraulic circuit 16 with hydraulic fluid. The valves and the like necessary for this purpose are known to the person skilled in the art and are therefore not shown. However, only a cross-flow flushing of the travel drive hydraulic circuit 16 and compensation of leakage losses occurring in the closed travel drive hydraulic circuit are preferably effected via the supply line 23. No drive energy is transmitted between the steering hydraulic circuit 19 and the travel drive hydraulic circuit 16 through this line. For leakage losses and cross-flow flushing, the travel drive hydraulic circuit 16 preferably has a travel return line 22 which opens into the tank 14, for example into the hydraulic tank. The steering hydraulic circuit 19 likewise preferably has a steering return line 21, in particular a steering return line 21. The travel return line 22 and the steering return line 21 are preferably combined and in this case lead as a common return line to the tank 15.

As is also shown in fig. 4, at least one rotational speed sensor 24 is preferably provided, which is connected to the electric machine 4 and/or to the drive motor 26. A plurality of rotational speed sensors 24 may also be provided in order to obtain corresponding data on the individual components. The rotational speed sensor 24 is in particular designed to measure the actual rotational speed of the motor 4 and/or the actual travel speed of the compactor 1 and to transmit the measured values to the control device 10. This is also shown in fig. 5. The dashed arrows in fig. 5 indicate the direction of the information flow, i.e. for example from the travel motor 26 via the speed sensor 24 to the control device 10 and also from the electric machine 4 via the speed sensor 24 to the control device 10. Further sensors that may be used are also shown in fig. 5. For clarity, these sensors are not shown again specifically in fig. 4 and 8. In particular, this relates to, for example, a temperature sensor 33 on the electric machine 4 and/or on the inverter 31 or converter and/or on the battery 32. Additionally or alternatively, a charge sensor 34 may also be provided on the battery 32. Furthermore, an ammeter 35 may be provided in order to determine the current level through the motor 4 and/or the inverter 31 or the converter. Also in addition or alternatively, a torque sensor 36 may be provided on the motor 4. Finally, a further temperature sensor 37 can also be provided, which determines the temperature in the steering hydraulic circuit 19. The measured values of all the sensors are transmitted to the control device 10 and are used by the control device as desired values for the operating parameters, except for the temperature in the steering hydraulic circuit 19. Furthermore, control device 10 preferably determines a desired value of the respective operating parameter under consideration, for example a desired rotational speed of motor 4 and/or a desired travel speed of compactor 1. For this purpose, the control device 10 is connected, for example, to an operating element 29 via which an operator can input control commands for controlling the compactor 1 to the control device 10. That is, the operating element 29 can be, for example, a steering lever or, for example, a brake lever. The control device 10 derives the desired rotational speed of the motor 4 and/or the desired travel speed of the compactor 1 from the respective presets given by the operator. Alternatively, these values may also be derived from the operating conditions or operating states of the compactor 1 or for safety reasons.

The temperature of the steering hydraulic circuit 19 can be used to ensure that the steering hydraulic circuit 19 does not overheat due to the provision of a braking torque on the steering charge pump 13. For example, it may be provided that a braking torque is provided at the steering feed pump 13 only if the temperature in the steering hydraulic circuit 19 is below a predetermined threshold value. The threshold value is then correspondingly selected such that reliable operation of the steering hydraulic circuit 19 and in particular of the steering device 27 is ensured.

That is, control device 10 preferably obtains both the travel presets of the operator and the actual values of the various parameters of compactor 1. For example, control device 10 may determine whether the determined actual value, for example, the rotational speed and/or the driving speed, exceeds a desired value, for example, by a predetermined threshold value and/or over a duration of the permissible time. At this time, based on these pieces of information, the control device 10 preferably controls the components of the compactor 1. The control device controls in particular the rotational speed of the motor 4, the delivery volume of the travel pump 12 and the flow resistance of the throttle valve 18.

Furthermore, the hydraulic accumulator 50 is optionally connected via a reservoir charging/discharging valve 51 to the hydraulic line 25 of the steering hydraulic circuit 19, in particular to the hydraulic line 25 between the steering feed pump 13 and the steering device 27, so that hydraulic energy can be stored at least temporarily and also fed into the steering hydraulic circuit (or also into other hydraulic circuits, in particular for driving working functions, such as for example raising and lowering an edge cutting device, etc.).

Fig. 6 shows a schematic time course for a specific application. The travel speed F of the compactor 1 will be discussed in particular herein. Such a process may be similarly or at least very closely applied to other operating parameters, so that only this is discussed below by way of example. In the illustrated graph, the time t is marked on the abscissa and the different parameters, which will be discussed in more detail below, are marked on the ordinate, respectively. This graph is set such that time t ₁ To t ₅ The same time is described in each of the graphs, respectively. The lowest graph thus shows the travel speed F of the compactor 1, for example, in terms of time. Here, the course of the actual value I of the travel speed F is shown, as well as the course of its desired value S. For example, compactor 1 is in operation until time t ₁ Is driven on a flat ground surface 8 at a constant driving speed F. From time t ₁ Initially, compactor 1 is driven down a slope, whereby compactor 1 is accelerated and travel speed F increases. At time t ₂ The travel speed F exceeds the desired value and up to the time t ₃ Acceleration continues. At time t ₃ The trend reversal occurs and the travel speed F decreases again until it reaches a time t ₄ Is again lower than the desired value S and at time t ₅ And re-reducing to the initial value. The uppermost graph shown shows the pressure drop p across the throttle valve 18. The pressure drop p is proportional to the braking torque produced, so that the braking torque is also shown by this graph. Since no braking torque is required on the steering feed pump 13 during normal operation of the compactor 1, the pressure drop p is reached until time t ₂ Are kept constant, for example zero. At time t when the actual value I of the travel speed F exceeds the desired value S ₂ The control device 10 actuates the throttle valve 18 and increases its flow resistance, fromWhile a pressure drop p occurs across the throttle valve 18. As a result of this pressure drop p, a proportional braking torque is also produced at steering feed pump 13, which can be used to support/counteract the torque occurring at travel pump 12 due to the coasting and thus to assist in the braking of compactor 1. Here, the control device 10 adjusts the braking torque in particular in proportion to the extent to which the actual value of the travel speed F exceeds the desired value S. At time t, due to, for example, insufficient braking torque to compensate for acceleration due to a slope ₂ And t ₃ The inter-drive speed F continues to increase, during which time the pressure drop p also increases and the resulting braking torque also increases. From time t ₃ From now on, the travel speed F decreases again. The pressure drop p across the throttle valve 18 is, however, at least in the case shown still maintained at the reached level by the control device 10 until the driving speed F is at the instant t ₄ And again to below the desired value. From this point on, the control device 10 reduces the pressure drop p again, for example to zero.

The two middle graphs in fig. 6 show the delivery volume V and the rotational speed D of the travel pump 12. The rotation speed D of the travel pump 12 is up to the time t ₃ Substantially follows the running speed F. The delivery volume V of the travel pump 12 remains constant up to this point. However, if the delivery volume V of the travel pump 12 is at this time t ₃ After which also the rotational speed D of the travel pump 12 is again reduced similarly to the travel speed F. However, in order to achieve an effective braking by the braking torque on the steering feed pump 13, it is advantageous if a sufficiently high torque is transmitted from the driving pump 12 to the steering feed pump 13. In order to achieve this during this time period of the method, it is preferably provided that the control device 10 actuates the travel pump 12 in such a way that the delivery volume V decreases. As the delivery volume V decreases, the rotational speed D of the travel pump 12 acting as a motor increases, or in this case at least remains constant, in order to be able to receive a volume flow from the travel motor 26 operating as a pump. In this way, the rotational speed D of the travel pump 12 is not reduced similarly to the travel speed F, and a higher rotational speed is transmitted to the steering feed pump 13 via the mechanical coupling 11, which is also guided by the steering hydraulic circuit 19 and in particular to the throttle valve 18 in this way The resulting volumetric flow achieves a higher braking torque. Thus, the braking performance can be improved in this way as a whole.

Fig. 7 shows a flow chart of the method 40. Method 40 begins with driving 41 travel pump 12 in travel drive hydraulic circuit 16 of compactor 1 by motor 4. The method further comprises driving 42 a steering feed pump 13 in a steering hydraulic circuit 19 of the compactor 1 by means of the motor 4. The steering supply pump 13 also feeds hydraulic fluid into the travel drive hydraulic circuit 16. The steering feed pump is coupled to the travel pump 12 via a mechanical coupling 11, so that a torque can be transmitted between the two pumps. It then proceeds to determine 43 an actual value of an operating parameter, for example an actual rotational speed of the motor 4 and/or an actual travel speed of the compactor 1 or a parameter associated therewith, and to determine 44 a desired value of said parameter, for example a desired rotational speed of the motor 4 and/or a desired travel speed of the compactor 1 or a parameter associated therewith. These values are in particular transmitted to the control device 10 or acquired by the control device. The control device 10 then compares 45, in particular, the actual value of the operating parameter, for example the actual rotational speed and/or the actual driving speed or a parameter associated therewith, with the desired value of the operating parameter, for example the desired rotational speed and/or the desired driving speed or a parameter associated therewith. In particular, the control device 10 determines that the actual value, i.e. for example the actual rotational speed and/or the actual driving speed or a parameter associated therewith, is greater than the desired value, i.e. for example the desired rotational speed and/or the desired driving speed or a parameter associated therewith. If this is detected, it is performed that a braking torque is generated 46 on the steering feed pump 13 via the hydraulic throttle 18. For this purpose, the hydraulic throttle 18 is preferably arranged in the hydraulic line 25 between the steering feed pump 13 and the steering device 27 in the steering hydraulic circuit 19. In particular, the hydraulic throttle 18 is actuated by the control device 10, so that the flow resistance of the throttle is increased. The torque required to overcome the flow resistance is provided as a braking torque on the steering feed pump 13 and can be transmitted to the travel pump 12 via the mechanical coupling 11. It is therefore carried out that the braking torque is transmitted 47 from the steering feed pump 13 via the mechanical connection 11 to the travel pump 12 of the travel drive hydraulic circuit 16. Alternatively and therefore shown in the figure by a dashed line, it is furthermore possible to reduce 48 the delivery volume V of the service pump 12 in order to ensure that, during the braking process, in spite of the reduction in the volume flow in the service drive hydraulic circuit 16 that occurs as a result, a rotational speed sufficient to provide a braking torque is transmitted to the steering feed pump 13.

Fig. 8 shows an alternative embodiment, in which the steering feed pump 13 and/or the working pump 14 are not driven by the electric motor 4, but can each have their own electric drive 30. The electric drive 30 can be configured, for example, as an electric motor. It is important that in this embodiment the travel pump 12 is also driven by the electric motor 4 and that a mechanical coupling 11 is present between the travel pump 12 and the steering feed pump 13. The mechanical coupling 11 can be formed separately from the output of the electric machine 4. For the other cases, the embodiment of fig. 8 is identical to the embodiment of fig. 4, so that reference is made to the description given so far for the purpose of avoiding repetition.

Furthermore, independently of the specific embodiment, a switchable clutch in particular can be simultaneously included by the mechanical coupling 11. In this way, the mechanical coupling between the travel pump 12 and the steering feed pump 13 can be interrupted, for example, at least temporarily.

Fig. 9 shows an alternative or complementary driving scheme with respect to this embodiment. The special feature here is that the travel motor 26, which is likewise integrated into the travel drive hydraulic circuit which is not shown in detail in fig. 9, is coupled to a separate brake hydraulic pump 54 of the brake hydraulic circuit with the respective throttle 18 by means of a transmission 56, for example a gear transmission. As a result, as is also shown in fig. 9, a separate brake hydraulic circuit can be associated with each individual travel direction, in particular with each individual compaction cylinder 5 of the compactor 1, and the braking action produced by the brake hydraulic circuit can be controlled individually. In this case, the travel motor 26 constitutes a means for directly driving the travel device 52.

Here, a hydraulic accumulator 50 with an accumulator charge valve 51 may also optionally be provided, wherein each of the two brake hydraulic circuits 53 may be assigned its own hydraulic accumulator 50 and thus separated from each other, or as shown in fig. 9, one common hydraulic accumulator 50 may be assigned to both brake hydraulic circuits 53 (or more than two brake hydraulic circuits). For this purpose, the common hydraulic accumulator 50 is connected to the two brake hydraulic circuits via respective connecting lines 57, 58, which in the present case merge in a common accumulator charging valve 51, but which can also be connected to the hydraulic accumulator via separate mutually independent accumulator charging valves 51. It is to be understood that the arrangement set forth in fig. 9 for two running gear in the compactor 1 may also be set up for only one running gear of the compactor.

In the drive variant shown in fig. 10, a particular feature is that the driving device 52 is actually driven directly by the electric machine 4, in particular without an intermediate hydraulic transmission stage, for which purpose a transmission 59 is interposed. Through this transmission, the electric motor is mechanically coupled to the brake hydraulic pump 54 and the other components 53 and 18, as already described with respect to fig. 9. For this embodiment, the hydraulic accumulator 50 can also optionally be connected to the brake hydraulic circuit via an accumulator charging valve 51.

For all the variants described in the exemplary embodiments with hydraulic accumulator 50, further hydraulic line branches may be provided, but these are not shown in the figures. These hydraulic line branches can be configured for supplying the hydraulic energy stored in the hydraulic accumulator 50 to other consumers, for example to work devices, such as edge cutting devices, etc., and/or for carrying out additional functions, such as, for example, a Boost function for a drive train.

Fig. 11 finally shows an exemplary profile of the rotational speed rpm of the motor, the profile of the driving speed, the delivery volume V of the driving pump 12 and the pressure p between the pump 13/54 and the throttle valve 18 for the embodiment shown in fig. 4. The illustrated quantitative profile here relates to a situation in which the compactor starts and accelerates on a level ground (t ₁ To t ₂ ) Running at a constant running speed (t ₂ To t ₃ ) And then re-braking to a stop (t ₃ To t ₅ ). In addition to the above description, it is important here that the pressure (t ₃ To t ₄ ) Braking is performed while at the same time significantly reducing the increase in the rotational speed of the motor. In order to achieve an effective braking process, the delivery volume V of the travel pump is reduced at the same time. In this way, an excessive increase in the rotational speed of the motor can be avoided even in this operating situation and at the same time the compactor is braked by means of the braking torque generated by the throttle valve.

The invention generally provides for efficient and reliable braking by means of a mechanical-hydraulic coupling with a throttle valve in a compactor having a hydraulic system driven by an electric motor and no longer having an internal combustion engine as a travel drive. Since the throttle valve is provided outside the travel drive hydraulic circuit, a series of advantages already mentioned above are obtained.

Claims

1. Method (40) for braking a compactor (1) operated by an electric motor (4), in particular a twin-drum compactor, a single-drum compactor, a rubber-wheel compactor or a trash compactor, comprising the steps of:

a) Driving the driving device (52) with a motor (directly or indirectly);

b) Determining (43) an actual value of an operating parameter;

c) -determining (44) an expected value of the operating parameter;

d) -comparing (45) the actual value of the operating parameter with the expected value of the operating parameter;

e) -generating (46) a braking torque by means of a hydraulic throttle valve (18) in a braking hydraulic circuit (53) comprising a braking hydraulic pump (54), in particular if the actual value of the operating parameter differs from the desired value, in particular if the actual value is greater than the desired value of the operating parameter, the throttle valve (18) being arranged in a hydraulic line with the hydraulic pump;

f) The braking torque is transmitted from the braking hydraulic pump (54) to a device (55) for driving the driving device (52) directly or indirectly via a mechanical coupling (11).

2. The method (40) according to claim 1, wherein the operating parameters are:

-the rotational speed of the motor (4), and/or

-the travel speed of the compactor (1), and/or

-the temperature of the motor (4) and/or inverter (31) and/or battery (32), and/or

-the charge of the battery (32), and/or

-the intensity of the current applied or output on the motor (4) and/or the inverter (31), and/or

-torque on the motor (4), or

-parameters associated with the above parameters, or

-a combination of at least two of said parameters.

3. Method according to any one of the preceding claims, wherein the compactor comprises a hydraulic system (6), in particular a twin drum compactor, a single drum compactor, a rubber wheel compactor or a trash compactor, the method comprising the steps of:

-in step a), driving (41) a travel pump (12) in a travel drive hydraulic circuit (16) of the compactor (1) by means of a motor (4);

-additionally driving (42) a steering feed pump (13) in a steering hydraulic circuit (19) of the compactor (1), the steering feed pump (13) also feeding hydraulic liquid into a travel drive hydraulic circuit (16), and the steering feed pump (13) being coupled with the travel pump (12) via a mechanical coupling (11);

-generating (46) a braking torque on the steering feed pump (13) by means of a hydraulic throttle valve (18) in step e), if the actual value of the operating parameter differs from the desired value, in particular if the actual value is greater than the desired value of the operating parameter, the throttle valve (18) being arranged in a hydraulic line (25) between the steering feed pump (13) and a steering device (27) in a steering hydraulic circuit (19); and is also provided with

-transmitting (47) a braking torque from the steering feed pump (13) to the travel pump (12) of the travel drive hydraulic circuit (16) via the mechanical coupling (11) in step f).

4. Method (40) according to any of the preceding claims, characterized in that a reduction (48) of the supply quantity (V) of the travel pump (12) is carried out during the transmission (47) of the braking torque.

5. The method (40) according to any one of the preceding claims, wherein,

the permissible range is set such that the generation (46) of a braking torque on the steering feed pump (13) and/or the generation of a braking torque on the steering feed pump (13) is only carried out if the actual value of the operating parameter exceeds a threshold value above the desired value of the operating parameter

The permissible time is set such that the generation (46) of a braking torque on the steering feed pump (13) is effected only if the actual value of the operating parameter increases relative to the desired value of the operating parameter over a longer time than the permissible time.

6. The method (40) according to the preceding claim, characterized in that the tolerance range and/or the tolerance time are adapted dynamically to the actual value of the operating parameter by a control device (10).

7. Method (40) according to any of the preceding claims, characterized in that a braking torque provided on a steering feed pump (13) is increased as soon as the difference between the actual value of the operating parameter and the desired value of the operating parameter increases, the braking torque being kept constant after the braking torque has been increased until the actual value of the operating parameter has been reduced again to the desired value of the operating parameter or below the desired value of the operating parameter.

8. The method (40) according to any one of the preceding claims, wherein the hydraulic system (6) comprises a working hydraulic circuit (17) separate from the travel drive hydraulic circuit (16) and the steering hydraulic circuit (19), the working hydraulic circuit (17) being driven only by a working pump (14) separate from the steering feed pump (13).

9. Method (40) according to any of the preceding claims, characterized in that the temperature in the steering hydraulic circuit (19) is determined and that no braking torque is generated on the steering feed pump (13) by means of the hydraulic throttle valve (18) when the temperature in the steering hydraulic circuit (19) is greater than a predefined threshold value.

10. The method (40) according to any one of the preceding claims, characterized in that the return line of the steering hydraulic circuit (19) and the return line of the travel drive hydraulic circuit (16) are combined and jointly led into the tank (15).

11. Method (40) according to any of the preceding claims, characterized in that a rotational speed change is performed when a braking torque is transmitted from the pump via the mechanical coupling (17) to a device, in particular a travel pump or a travel motor, which directly or indirectly drives the travel device (52).

12. Method (40) according to any one of the preceding claims, characterized in that the travel hydraulic motor is coupled via a mechanical coupling with a brake hydraulic pump, in particular configured with an adjustable delivery volume, which is part of a brake hydraulic circuit separate from a travel drive hydraulic circuit (16), and in that the hydraulic throttle (8) is arranged in the brake hydraulic circuit, in particular downstream of the brake hydraulic pump, the method having the steps of: the hydraulic throttle (18) enables a braking torque to be generated (46) on the braking hydraulic pump and the braking torque to be transmitted (47) from the braking hydraulic pump via the mechanical connection (11) to the travel hydraulic motor of the travel drive hydraulic circuit (16).

13. Method (40) according to any one of the preceding claims, characterized in that the brake hydraulic circuit comprises a hydraulic accumulator (50), in particular connected downstream of the hydraulic throttle valve (18) via an accumulator charging valve (51), the charging of the hydraulic accumulator (50) being performed by hydraulic fluid delivered by a brake hydraulic pump in the brake hydraulic circuit.

14. Compactor (1), in particular a twin-drum compactor, a single-drum compactor, a rubber-wheel compactor or a refuse compactor, having a hydraulic system (6), an electric motor (4) and a control device (10), characterized in that the control device (10) is configured for carrying out the method (40) according to any of the preceding claims.

15. Compactor (1) according to the preceding claim, characterized in that,

the compactor has at least one of the following features:

-the compactor has a travel drive hydraulic circuit (16) with a travel pump (12) driven by an electric motor (4), the travel pump (12) being in particular configured as a variable displacement pump;

-the compactor has a steering feed pump (13), in particular driven by an electric motor (4), in a steering hydraulic circuit (19), the steering feed pump (13) being in particular configured as a dosing pump, for example as a gear pump;

-the steering feed pump (13) is configured for feeding hydraulic fluid into a travel drive hydraulic circuit (16), in particular configured as a closed circuit;

-the travel pump (12) is coupled to the steering feed pump (13) by a mechanical coupling (11);

-providing a hydraulic throttle valve (18) in a hydraulic line (25) between a steering feed pump (13) and a steering device (27) of a steering hydraulic circuit (19);

-the hydraulic throttle valve (18) is configured as a proportional pressure limiting valve;

-said hydraulic throttle valve (18) is configured to be controllable by said control device (10);

-providing a working hydraulic circuit (17) separate from a travel drive hydraulic circuit (16) and a steering hydraulic circuit (19) with a working pump (14), said working pump (14) being in particular in driving connection with said electric motor (4);

-the steering feed pump (13) and the hydraulic line supplied by the steering feed pump are configured as pilot-less valve;

-providing a rotation speed sensor (24) on the electric machine (4) and/or on a travel motor (26) of the travel drive hydraulic circuit (16), said rotation speed sensor being connected to the control device (10);

-the rotational speed sensor (24) is configured for determining an actual rotational speed of the motor (4) and/or an actual travel speed of the compactor (1) or a parameter associated therewith;

-providing a temperature sensor (33) on the electric machine (4) and/or on the inverter (31) and/or on the battery (32), said temperature sensor being connected to the control device (10) and being configured in particular for determining the actual temperature of the electric machine (4) and/or the inverter (31) and/or the battery (32);

-providing a charge sensor (34) on the battery (32), said charge sensor being connected to the control device (10) and being configured in particular for determining an actual charge of the battery (32);

-an ammeter (35) is provided on the electric machine (4) and/or on the inverter (31), which ammeter is connected to the control device (10) and is in particular designed for determining the actual current strength through the electric machine (4) and/or through the inverter (31);

-providing a torque sensor (36) on the electric machine (4), said torque sensor being connected to the control device (10) and being configured in particular for determining an actual torque of the electric machine (4);

-a temperature sensor (17) is provided in the steering hydraulic circuit (19), which is connected to the control device (10) and which is in particular configured for determining the actual temperature of the steering hydraulic circuit (19);

-the control device (10) is configured for determining, in particular from a setting of an operating element of the compactor (1), a desired value of an operating parameter, in particular a desired rotational speed of the motor (4) and/or a desired travel speed of the compactor (1) or a parameter associated therewith;

-the control device (10) is configured for generating a braking torque on the steering feed pump (13) via the hydraulic throttle (18) when the actual value of the operating parameter is greater than the desired value of the operating parameter, in particular when the actual rotational speed and/or the actual driving speed or a parameter associated therewith is greater than the desired rotational speed and/or the desired driving speed or a parameter associated therewith;

-the return line of the steering hydraulic circuit (19) and the return line of the travel drive hydraulic circuit (16) are configured to open together into the tank (15);

-having a hydraulic accumulator (50) connected to the steering hydraulic circuit (19) via an accumulator charging valve (51).

16. The compactor machine (1) according to any of the preceding claims 14 or 15, characterized in that it has at least one of the following features:

-the compactor comprises a travelling device (52) directly driven by a hydraulic motor, in particular via a shaft, and a brake hydraulic pump (54) mechanically connected to the hydraulic motor, in particular via a transmission chain;

-the compactor comprises a travelling device (52) directly driven by an electric motor, in particular via a shaft, and a coupling transmission via which the electric motor can be mechanically coupled to a brake hydraulic pump of a brake hydraulic circuit, in particular comprising a hydraulic throttle (8) downstream of the brake hydraulic pump.

17. Compactor (1) according to one of the preceding claims 14, 15 or 16, wherein each travel device (52), in particular each compaction drum (9), comprises its own brake hydraulic circuit separately from one another and furthermore has at least one of the following features:

-each hydraulic circuit is provided with a separate hydraulic accumulator;

the hydraulic pressure of the hydraulic brake system is controlled by a hydraulic pressure control system, which is connected to the hydraulic brake system via a hydraulic brake system, and is connected to the hydraulic brake system via a hydraulic brake system;

the throttle valves of the two brake hydraulic circuits can be actuated independently of one another, and the control device (10) is configured such that it controls the two throttle valves independently of one another and/or taking into account the actual driving direction.